Date: Fri, 14 Feb 2003 14:59:29 +0100 From: Roman Neuhauser <neuhauser@bellavista.cz> To: Bjarne Wichmann Petersen <freebsd.nospam@mekanix.dk> Cc: dan@slightlystrange.org, freebsd-questions@FreeBSD.ORG Subject: Re: Resolving or blocking eg. doubleclick.net? Message-ID: <20030214135929.GI81356@freepuppy.bellavista.cz> In-Reply-To: <200302121443.38094.freebsd.nospam@mekanix.dk> References: <200302121029.14713.freebsd.nospam@mekanix.dk> <200302121301.14497.freebsd.nospam@mekanix.dk> <20030212121531.GB60013@catflap.home.slightlystrange.org> <200302121443.38094.freebsd.nospam@mekanix.dk>
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# freebsd.nospam@mekanix.dk / 2003-02-12 14:43:37 +0100:
> On Wednesday 12 February 2003 13:15, Daniel Bye wrote:
> > At a shell prompt, try
> > $ time host doubleclick.net
>
> $ time host dk.doubleclick.net
> dk.doubleclick.net mail is handled (pri=10) by relay2.doubleclick.net
> dk.doubleclick.net mail is handled (pri=10) by relay1.doubleclick.net
>
> real 0m0.269s
> user 0m0.000s
> sys 0m0.005s
>
> $ time host dk.doubleclick.net
> dk.doubleclick.net mail is handled (pri=10) by relay1.doubleclick.net
> dk.doubleclick.net mail is handled (pri=10) by relay2.doubleclick.net
>
> real 0m0.009s
> user 0m0.004s
> sys 0m0.001s
>
> So, it's safe to assume my cache is working? ... and perhaps, resolving
> doubleclick.net et al isn't the issue?
>
> But looks like the cache expires after a couple of minutes?
That's something you can easily check by trying to resolve the name
a couple of minutes later. :)
But that would be a lame test, and you wouldn't really know any hard
data. This is authoritative:
roman@freepuppy ~ 1011:1 > dnsq a doubleclick.net ns2.dcny.doubleclick.net|grep ^answer
answer: doubleclick.net 300 A 199.95.206.210
roman@freepuppy ~ 1012:0 >
so yes. the A RR for doubleclick.net has TTL of 300 seconds.
somewhat stupid if you ask me.
I would suggest you to configure your DNS cache so that it forwards
queries to your ISP's caches. That'll buy you some time.
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